AFRICAN

ORCHIDS

Microcoelia hirschbergii Summerh., Bot. Mus. Leafl. 11: 146 (1943).
Description:
Stem short, up to 10x2.0 mm. Scale-leaves acute to ± rostrate, with c. 6 nerves, up to 4.0 mm long. Roots many, ± radially spreading, densely crowded, slightly un dulating, unbranched or with few branches, mostly characteristically attached to the substrate forming a ± conical tuft, terete to slightly flattened, smooth, up to 90 x 1.5-3.0 mm. Inflo-rescence(s) short, erect, spreading, up to 15-35 mm long, up to 4(—8) simultaneously, usually dense, each with up to 15 flowers, ± concentrated apically; peduncle indistinct; rachis ± straight, terete, ± excavated at the bracts, acicu-lated, slightly swollen below the bracts, (oil green); bracts only sheathing at the very base, all the rest not sheathing, ovate, ± acuminate, 1-nerved, 0.8-2.5 mm long, whitish transparent with a central band tinged with (vinaceous-rufous to English-red). Pedicel long, ± straight, furrowed, up to 3.5(-7.4) mm long, whitish; ovary ± straight, distinctly furrowed, valves ± sharply keeled, (1,3-)1.7-3.2(-4.4) x 0.6-0.9 mm, whitish tinged with (cream-buff). Flowers ± erect-spreading, up to 7.5(—11.4) mm long including ovary; tepals pure white, labellum pure white, at base rust-brown to greenish brown; column at base rust-brown, frontally dark green; anther dark green. Glandular hairs very sparse, mainly distributed on rachis, base of bracts, pedicel and ovary, basal parts of the perianth to the apex of the spur. Dorsal sepal ovate, acute, subapiculate, 3-nerved, distinctly thickened along the central nerve, apically ± recurved, 2.3-4.0 x 1.0-2.0 mm. Lateral sepals slightly asymmetric, ovate, acute, apiculate; 3-nerved, distinctly thickened along the central nerve, apically ± recurved, 2.8-4.0 x 1.3-1.8 mm. Petals elliptic to ovate, acute, 1-nerved, indistinctly thickened along the central nerve, 1.4—4.0 x 0.8-1.6 mm. Labellum 3-lobed; mid-lobe ovate, acute to subacuminate, ± folded, with an obtuse conical-shaped thickening at each side of spur mouth, with 3 nerves, lateral nerves much branched; side-lobes small, rounded, 1.9-3.7 x 1.7-2.9 mm; pure white except for a semicircular band around the frontal spur mouth including the two thickenings (vinaceous-rufous); spur straight, slightly appressed to the ovary or ± dependent, cylindrical, at the base constricted, evenly inflated apically, obtuse, (2.7-)5.4 - 6.6 mm long, up to 1.3 mm in diameter apically Column short, truncate, side-lobes slightly infolded, 0.3 - 0.8 mm long and 0.7-1.0 mm high, (vinaceous-rufous) tinged with (citrine) in the front; androclinium shallowly excavated with a small central hump, (citrine); rostellum-lobes short, obtuse, ± deltoid, up to 0.5 mm long, (citrine). Anther semiobovate in side view, deeply incumbent apically, tapering into a short recurved apex, 0.7-0.8 x 0.6-1.0 mm, (dark citrine), the very apex (straw yellow). Pollinia asymmetric; in side view elliptic to obovate, 340-450 x 300-360 µm in median section ± obovate, up to 270 µm thick, (primrose yellow). Stipes ligulate, slightly spathulate apically, ± sigmoid, (230-)300 - 530 µm long, apically 60-110 µm wide, transparent; viscidium ± oblong to transversely elliptic, obtuse, notched at both ends, membranous, 280-470 x 300 - 390 pm. Capsule ellipsoid, up to c. 7.5 x 2.5 mm; pedicel distinct, up to 8 mm long, whitish (at the time of dehiscence). Seeds fusiform to bottle-shaped, testa cells narrowly elongate (in a dry state), beset with ± club-shaped or more sparsely with hook-shaped processes; anticlinal walls ± sulcate, with finer striations, terminal extensions indistinct or ± loop-shaped, (290-)320-390 (—420) x 60—90 µm (25 dry seeds measured). Scent not percepted.
Habitat:
Mainly in wetter woodland bordering wet seepages (dambos) (Williamson in litt.), and riverine forest. Epiphytic on trees and bushes, mostly confined to smaller branches and twigs, often on more or less loosely barked substrates.
Flowering period:
In the transition to, but before the main rains in the late rainy season.
Cultivation:
As given for the genus, warm to cool growing epiphyte.
Notes:
A striking little species with a rather long cylindrical spur slightly narrower towards the mouth. The rostellum and also the stipes of the pollinium are exceptionally short the viseidium is relatively large being as broad us the stipes is long, while the pollinia are larger than either.
Distribution:
S. Zaïre to Zambia
References:
The Orchids of South Central Africa Williamson 1977; A Monograph of the Genus Microcoelia [Orchidaceae] Jonsson 1981; Flora Zambesiaca Vol 11 Part 2 Pope 1998; Angraecoid Orchids Stewart, Hermans and Campbell 2006 ;WCSP (2017). 'World Checklist of Selected Plant Families. 03.03-2017; http://apps.kew.org/wcsp/
Images:
Click on each image to see a larger version.

Habitat/In situ Habitat/In situ
Microcoelia hirschbergii 01 Microcoelia hirschbergii 02
Photograph© Lourens Grobler. Image used with kind permission. Photograph© Lourens Grobler. Image used with kind permission.